Takahashi em-500

[PhotoGav]

I am helping a friend get their observatory up and running with a Takahashi em-500 mount and I have come up against a problem… I was trying to polar align the mount yesterday evening and it just won’t reach a high enough altitude to get Polaris into the polar scope reticle. The mount gets stuck against the ‘cradle’ piece just above the altitude adjustment bolt. Here’s a pic:

 

You can see the scratch marks where it gets blocked. From the side views, it looks like the two parts of the mount are slightly out of alignment:

 

 

 

My final question is: what does the bolt in the middle of the black logo ring do?

 

I’m hoping there is a Tak mount expert out there who will be able to help me out. 
 

Thanks,

Gavin. 

[CraigT82]

Sorry not a Tak expert, but have you seen this? Where is the observatory located? 
 

[Tomatobro]

That was my first thought that the mount was not designed for northern latitudes. Not the end of the world as it needs a tapered mounting plate under the mount to give it more angle and bring it within the adjustment range

[PhotoGav]

Thank you for the swift responses. The thought had crossed my mind that it might be for lower latitudes, but I couldn't find any details anywhere. @CraigT82 where did you find those specs?

That answers the problem perfectly and I now have a solution to pursue. 

[PhotoGav]

Don't worry, I've seen the web site at the bottom of the specs and have found that online. Thank you!

[PhotoGav]

Are there any issues with adding in a tapered slice to tilt the mount backwards enough to allow alignment? Given that the mount would no longer be level, would it affect the performance in any way? (I am wondering if that is a really silly question?!??!).

Also, do you have any suggestions for suitable manufacturers of such a tapered slither?!

Thank you.

[Tomatobro]

Its the axis that is aligned with the pole so getting the mount level is not an issue. Yes I know that manufacturers add bubble levels but that is because users expect to have to level the mount base as part of the setup.

Take a look at the latest version of the MESU 200 mount. It uses a welded angled "wedge" . Something like that could be fabricated.

Steel disc's are available on Ebay of various thicknesses along with bar offcuts so the challenge would be drilling and tapping as required, boring hold down bolt access holes and welding.

Given that the mount already goes to 50 degrees the angle only needs to be 5 degrees to get the mount within its adjustment range.

[JeremyS]

1 hour ago, PhotoGav said:

Are there any issues with adding in a tapered slice to tilt the mount backwards enough to allow alignment? Given that the mount would no longer be level, would it affect the performance in any way? (I am wondering if that is a really silly question?!??!).

Also, do you have any suggestions for suitable manufacturers of such a tapered slither?!

Thank you.

No it will be fine. With EQ even the tripod does not need to be level. It’s alignment of the PA with the pole that counts.

When I lived in Singapore, on the equator , ppl with Losmandy mounts had to use a wedge as the mount wasn’t designed to get below a few degrees of latitude 

[PhotoGav]

Perfect, thank you folks, that makes sense. Engineering solutions will be worked on!

[Tomatobro]

looking at the pier and adapters I made for mine I think it would be possible to slash cut the four spacers at (say) a five degree angle to sandwich the top plate between a top and bottom spacer and still have the bolts vertical. The holes in the sandwiched plate would have to be large enough to accommodate the angle but when bolted down would still be ridged.

Just an idea

[tomato]

Would something like this work, no bespoke machining required:

https://www.zoro.co.uk/shop/fasteners/square-washers/square-taper-washer-8%-metric-steel-grade-hv10-din-434/f/56445

[Mr Spock]

This is probably sacrilege, but, have you thought about taking the mount apart and filing down the edge? You only need it to tilt a couple more degrees.

[PhotoGav]

Thank you for the suggestions. I’ll take the mount off the pier later in the week and hopefully it will be obvious what the best approach will be. But please keep coming with ideas!

[Stardust1]

I had an EM-200 which had an elevation adjustments of max 50 degrees. I live above 50 degrees latitude. Under the tripod leg that was pointing to the north I would put a piece of wood. That worked for me. The Tak mounts doesn't have to be leveled. 

Takahashi solution for those living above 50 degrees latitude, is their level adjusters in Tak blue color 😃

Edited November 9, 2022 by Stardust1

[Ibbo!]

Had the same with my NJP and until I installed the pier (took a long time) it had a bit of paving stone under the tripod leg.

 

 

 

[PaulE54]

I'd be wary of tilting tripod legs since it may bring the Centre of Gravity of the whole assembly worryingly close to tipping over. Keep the tripod level, keep the CoG of the whole assembly central within the area of the tripod legs, and tilt the mount attachment to the tripod using shims as described above. Safer!

Paul

[PhotoGav]

I am happy to report that some washers have provided the necessary tilt to the pier adapter. I successfully polar aligned the mount this evening and all is good. Thank you all for your help and advice.

[F15Rules]

57 minutes ago, PhotoGav said:

I am happy to report that some washers have provided the necessary tilt to the pier adapter. I successfully polar aligned the mount this evening and all is good. Thank you all for your help and advice.

Just came across this thread but I see you've got a solution..

I have an EM2 mount which also has a maximum of 50 degrees setting. I'm at just over 53 degrees north and a piece of compressed rubber about 12mm thick and 60mm long placed under my north facing wooden tripod foot gets Polaris inside my reticule and quite sufficient for me to track an object for c 1 hour (I'm visual only so that's plenty for my needs).

No worries about the tipping point of the mount if the scope is properly balanced once the "equalising shim/washers/plate" etc is in position..

That EM500 looks quite a beast!👍.

Dave

Edited November 12, 2022 by F15Rules
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[PhotoGav]

Ha! Yes, the EM-500 is a big old thing, it’s carrying a Mewlon 300 - not a bad scope! I had a bit of a wander around the skies once aligned, lovely views of Jupiter, core of M31, Ring Nebula, M15, Almach, the Double Double and the Owl Cluster. Tried Mars too, but too low and was a featureless orange blob!